More particularly, the invention relates to a sensor comprising:                a casing delimiting an internal volume internal to the casing and having a passage extending between this internal volume and a first external zone external to the casing;        a moving part able to move inside the said internal volume of the casing;        detection means for detecting a movement of the said moving part with respect to the casing, these detection means comprising a detection portion extending in the passage, between the said first external zone external to the casing and the said internal volume internal to the casing, this detection portion also having a groove open to the outside of the detection portion, this groove extending between the said first external zone external to the casing and the said internal volume internal to the casing.        
That portion of the detection means which is positioned in the passage of the casing has a groove open to the outside. This groove, formed on the detection means, allows angular positioning of the detection portion with respect to the casing.
Such a sensor may malfunction in cold conditions, because, cold/Ice may prevent the moving part from sliding in the internal volume.